Automatic underfeed stoker



N A M A E s M G AUTOMATIC UNDERFEED STOKER Filed Feb. 12, 1938 2 Sheets-Sheet l INVENTOR, Qz'Zberi/V'Seavzan,

3M ATTORNEY' N A M A E S M a AUTOMATIC UNDERFEED STOKEW Filed Feb. 12, 1938 2 Sheets-Sheet 2 E N R o T T A Patented Apr. 15, 1941 UNITED STATES PATENT OFFICE.

2,238,232 AUTOMATIC UNDERFEED- sroKEn Gilbert M. Seaman, Catskill, N. Y.

Application February 12, 1938, Serial No. 190,196

6 Claims.

This invention relates to stokers and furnaces and more particularly to automatic coal stokers for domestic furnaces, though it is noted that in most of the claims the invention is not limited to domestic stokers. or furnaces.

One object of the invention is to provide an improved assembly of this kind in which the various parts are efiiciently maintained in proper relation.

Other objects of the invention are to provide efficient and improved arrangements for driving the stoker, ash remover and blower, and an improved grate, fire box and ash receiver.

Additional objects of the invention are to improve generally the simplicity and eificiency of such apparatus and to provide an extremely simple apparatus of this kind which is economical, durable, and reliable in operation, and economical to manufacture and install.

Still other objects of the invention will appear as the description proceeds; and while herein details of the invention are described in the specification and some of the 'claims, the invention is not limited to these, since many and various changes may be made without departing from the scope of the invention as claimed in the broader claims.

The inventive features for the accomplishment of these and other objects are shown herein in connection with an improved furnace and stoker which briefly stated, includes ablower housing and lower hopper portion integral with each other and respectively communicating with coaxial air feed and coal feed tubes.

A fire pot communicating with the air feed tube carries therein a grate and an elbow member having its. upper end opening into the grate and its lower end joining the coal feed tube. An ash receiver is disposed beneath the fire pot; and an ash conveyor tube joins said receiver.

Shafts having feed screws thereon are disposed in said conveyor tube and coal feed tube and receiver, and are driven by unitary means used also for driving the blower.

This improved automatic stoker can be readily installed without danger of its several members becoming loose or getting out of alignment, since whenever practicable the members are welded together.

The housing of the chain conveyor is bolted or otherwise secured to the coal feed unit for support. The fire pot is constructed with spaced tuyre rings to support the burning coal.

In the drawings- Fig. 1 is a front elevation showing the driving mechanism, air blower, coal magazine and ash conveyor; 1

Fig. 2 is a longitudinal vertical sectional view taken on the line 2--2 of Fig. 1 showing the coal feed, fire pot, and ash remover mechanism;

Fig. 3 is a plan View of the fire pot, showing the grate; i

Fig. 4 is. an enlarged fragmental sectional view taken on the line 4-4 of Fig. 3, showing the means for attaching the grate tuyre rings-t0 the retort;

Fig. 5 is an enlarged fragmental plan of the coal feed tube and elbow, taken onthe line 5;--5 of Fig. 2;

Fig. 6 is a sectional taken on the line 66 of Fig. 5;

Fig. 7 is an enlarged sectional View, taken on the line of Fig. 2, showing the manipulating means for the cleanout rod;

Fig. 8 is a fragmental plan taken on the line 8--8 of Fig. 2, showing the lower retort member welded to the coal and air pipes;

Fig. 9 is a vertical sectional view taken on the line 9-9 of Fig. 2, and showing the ash removing means;

Fig. 10 is a fragmentary horizontal sectional view taken on the line Ill-40 of Fig. 4;

Figs. 11 and 12 are fragmentary rear elevation and vertical section of the blower inlet closure.-

Referring to the drawings, particularly to Figs. 1 and 2, therein is shown a complete coal feeding and ash removing apparatus, having a coal magazine C secured to the lower coal hopper portion 0', integrally attached to a blower housing. B (Fig. 1) having an inlet opening 3 (Fig. 12) across which is disposed a spider to carrying an axial screw 312 on which is rotatably and longitudinally mounted a closing member 30 held in placeby jam nuts 3d and having a handle lug 3e, wherebythe air-inlet to the main body portion 2 of the blower is controlled.

Magazine C and lower portion c are secured together by means of bolts passing through brackets H, 12 (Fig. 1) mounted on the lower portion and magazine respectively.

The blower B is provided with an air discharge duct A (Fig. 2), which discharges into the lower portion of the fire pot, as will be explained. The blower B is also provided on its outer peripheral portion with a lug 6 pivotally supporting a bracket 58 to which in turn is secured a motor M having pulley 60. Said motor bracket 56 is held in a yieldably raised position by a spring 9 carried on an adjusting rod 8- supported by a lug I on the blower housing.

A speed reducing mechanism S (Fig. 1) is adjustably positioned, on a bracket 4 on front of the blower B, by means of an adjusting screw 5 disposed in an upturned flange on the end of the bracket 4, the bracket being integral with the blower housing. The speed reducing mechanism is provided with a motive pulley 6| driven by a belt 59 from the pulley 60 of the motor M, thereby driving the blower. The speed reducing unit S is also provided with a sprocket 62 adapted, by means of a chain 61, to drive, at reduced speed, sprockets 63 and 64, respectively loosely rotatable on a coal propeller shaft I3 and an ash remover shaft 65 rotatable in the flanged bearing in the side of the conveyer housing B. To pre vent breaking the chain in case a jam develops in the coal or ashes being fed, I provide levers 69, 69 secured fast to the shafts I3 and 85 respectively and provided with driving pins 18, 19

formed of soft metal which engage in holes in the sprockets 63 and 64 and serve as drive members to drive the said shafts. If an overload should occur, the soft metal pin will shear and no damage will be done to the driving means.

The lower front side of the lower portion of the coal hopper is provided with a hole I0 (Fig. 2) in which is disposed a bushing supporting a thrust bearing I2 receiving a feed screw shaft I3 disposed in. a sleeve I6 extending from the lower portion 0 of the hopper opposite the hole Ill. The outer end ll of the said sleeve I6 is shouldered to receive a pipe T, which is welded in the said shoulder and extends to the fire pot member R.

The coal feed screw shaft I3 is disposed also within the tube T and is provided with a screw l4 extending from the fire pot to a collar I5 carried on said shaft I3. Said shaft extends through the bearing II and loosely carries the sprocket 63, the lever 69 being fast on the shaft.

The air blower B is provided with adjustable legs P (Fig. 1), only one of which is shown. The blower housing is formed integral with the lower portion 0 of the hopper and has a surrounding conduit portion 2' (Fig. 2) around the sleeve portion I6, I! of the hopper, which conduit portion 2' forms an air duct A leading directly from the blower. The conduit portion 2' is provided with an outer extended portion I8 receiving and welded to a pipe T which surrounds the coal feed pipe T and extends to the fire pot housing, thus forming an air duct from the blower B to the fire pot. A cut-off wall 2 separates the lower portion of the space 0. within the conduit portion 2' from the interior of the blower housing.

The fire pot R is formed with two conical sec tions as I9 and 29 (Fig. 9) secured together by bolts 29 passing through flanges 21, 28. The upper section 20 has a wide flanged opening as at 33 (Fig. 2) and contains a series of spaced tuyre rings 34. The lower section I9 is provided with an outlet portion 2| surrounding the outlet portion 22 of the elbow 25, said portions respectively receiving the end portions of the tubes T and T. The portion 22 extends as an elbow, as at 25, up into the fire pot, and is secured in position by a rib 26 (Figs. 2 and 8) extending from the wall of the lower fire pot member IS. The lower part of the member I9 is provided with a clean-out opening 23 provided with a removable closure 24, for cleaning the interior of the fire pot.

The uppermost tuyere ring 34, Fig. 4, is held in place and spaced from the flange 32 by means of flanged pins 35 passing through said flange and the lug 48, see also Fig. 3, on said ring.

The inner diameters of the other tuyere rings are downwardly progressively smaller, and have downwardly and inwardly beveled inner faces forming a conical fire pot. The lowermost ring is provided with a lug 39 secured by a screw 31 to a lower ring lug 38 on the upper fire box section; and all of the rings are held spaced by collars 35 intermediately formed on pins 35 received in vertically alined holes of adjacent rings. This provides air spaces 4| (Fig. 4) whereby air enters the fire to support combustion of the fuel, the fuel resting on ledges 42, thereby relieving the screw conveyor I4 of some effort.

The pipe T is welded, as at W, to the portion 2| of the fire pot housing I9, thus insuring a slip proof joint and also a leak proof connection from the blower to the fire pot.

Coal from the hopper C is forced by the screw I4 through the sleeve I8, the pipe T, up through the elbow 25 into the interior of the grate formed by the tuyre rings 34,

As the coal continues to be fed upwardly into the grate and burned, the ashes collect on the flange 32 and spill over upon the aprons 95 (Figs. 2 and 9) by which the ashes are guided into the trough 82 in which is disposed the feed screw 66 on the shaft 85.

The trough 92 is formed by slitting and spreading open a tube to form side portions 94 on which the aprons rest, the end portion 93 of the tube being left to receive the tube T". The outer end of the tube T" is received in the extension 3| of the conveyor housing D.

The ashes are conveyed along the tube T" to the lower end of a conveyor housing D from which they are scooped by buckets 68 on a sprocket chain 78 passing through the upper part E of the conveyor housing over the lower sprocket I8 and over the upper sprocket 19 carried on a shaft 8| rotatable in bearing openings in a U- shaped member 83 guided between gibs or guideways 88 on the sides of the housing. Said U- shaped member is yieldably held in upper chaintensioning position by a chain tightening means 82 including a spring 85 carried on a threaded stem 84 loosely received in a bore in said member 83, said spring being compressed between said member and jam nuts 86 on the lower part of the stem. The lower end of the stem is screwed into a lug 81 on the housing wall and held by a nut. After the buckets pass over the upper sprocket, the ashes are dropped therefrom through an opening 88 in the housing and into a suitable receptacle 89.

The housing D is mounted on the hopper c' by means of brackets I3 and carried on the hopper and housing respectively and held together by rivets or bolts ll.

The air in air conduit A is forced into the fire-box space A2 around the grate and hence through the fire and up the chimney flue. In order to prevent any of the combustion gases from being forced back through the elbow and back and out through the tube T, air under pressure is discharged from the passage A through an arcuate opening 46 (Figs. 2, 5 and 6) in an offset portion of tubular portion 22, said opening discharging directly into the space A in the elbow 25, thereby to form a barrier of clean air under sufiicient pressure to prevent combustion products from working back into the tube T.

To prevent the opening 46 from getting stopped up with ashes, dust or the like, there is provided an arcuate scraper or cleaner 4B, normally resting in but not entirely filling the opening 46. Said cleaner comprises a flat arcuate bar secured across the end of a flat bar or rod 41 slidable along the top of the tube T and provided at its outer end with a perforation receiving a pin or screw 50 (Fig. '7) passing up through a longitudinal slot 54 in the tube T and carrying a manipulating knob 49.

To prevent escape of air through the slot 54, the slot is covered with a cover plate 5| extending at all times beyond the ends of the slot and having a central perforation whereby the cover plate is received on the screw 50.

A shoe 52 slidably conformally engages the inner face of the tube T and is provided with a perforation receiving the screw 50 and with lugs 53 at both edges of the bar 41 to prevent the shoe from twisting on the bar.

To clean out the opening 46, the attendant merely reciprocates the bar 41 and cleaner 48 by grasping and reciprocating the knob 49.

I claim as my invention:

1. In combination, air feed and coal feed tubes; a downwardly tapered fire pot comprising an up-- per portion provided with upper inner and outer fianges and lower inner and outer lugs, and a lower portion having upper outer lugs secured to said lower outer lugs, said lower portion communicating with the air feed tube; a grate in said fire pot including superposed flat spaced rings of progressively smaller inner diameter, the upper and lower rings thereof having outer lugs secured to said upper inner flanges and said inner lugs of the upper portion respectively; and a tubular portion in the lower part of the fire pot establishing communication between the lower part of the grate interior and the coal feed tube.

2. In combination, fire pot comprising an upper portion provided with upper inner and outer flanges and lower inner and outer lugs, and a lower portion having upper outer lugs secured to said lower outer lugs, and a grate in said fire pot including superposed spaced rings, the upper and lower rings thereof having outer lugs secured to said upper inner fianges and said inner lugs of the upper portion respectively.

3. In combination, air feed and coal feed tubes; at downwardly tapered fire pot comprising an upper portion provided with an upper inner flange provided with holes and an outer flange and lower inner and outer lugs said lugs provided with holes, and a lower portion having upper outer lugs provided with holes secured to said lower outer lugs with screws, said lower portion communicating with the air feed tube; a grate in said fire pot including superposed fiat spaced rings of progressively smaller inner diameter, the upper and lower rings thereof having outer lugs secured to said upper inner flanges with pins and to said inner lugs of the upper portion with screws respectively; and a tubular portion in the lower part of the fire pot establishing communication between the lower part of the grate interior, and the coal feed tube.

4. In combination, coaxial air feed and coal feed tubes; a fire pot communicating with the air feed tube; a grate in the fire pot; and an elbow member having its upper end opening into the grate, and a laterally turned lower end receiving the coal feed tube; said laterally turned end being provided with an opening from the airfeed tube into the elbow portion; the air feed tube being provided with a longitudinal slot; a scraper bar in said opening; a rod longitudinally slidable in the air-feed tube and secured to said bar and carrying a member projecting through said longitudinal slot and provided with an exterior handle; a cover plate over said slot provided with a perforation receiving said member; and a shoe engaging the inner face of the air feed tube and having a perforation received on the member, and preventing the escape of air..

5. In combination, an air feed tube provided with a longitudinal slot; a rod longitudinally slidable in the air-feed tube and carrying a member projecting through said longitudinal slot and provided with an exterior handle; a cover plate over said slot provided with a perforation receiving said member; and a shoe engaging the inner face of the air feed tube and having a perforation received on the member, and preventing escape of air.

6. In combination, coaxial air feed and coal feed tubes; a fire pot communicating with the air feed tube; a grate in the fire pot; and an elbow member having its upper end opening into the grate, and a laterally turned lower end receiving the coal feed tube; said laterally turned end being provided with an opening from the air-feed tube into the elbow portion; the air feed tube being provided with a longitudinal slot; a scraper bar in said opening; a rod longitudinally slida-ble in the annular portion between said tubes and secured to said bar and carrying a member projecting through said longitudinal slot and provided with an exterior handle; a cover plate over said slot provided with a perforation receiving said member; and a shoe engaging the inner face of the air feed tube and having a perforation received on the member, and provided with lugs at the edges of said rod to prevent said shoe from twisting on said rod.

GILBERT M. SEAMAN. 

